Question

Nickel metal will react with CO gas to form a compound called nickel tetracarbonyl (Ni(CO₄)) which is gas at temperatures above ~45C.

A 1.50 L glass bulb is filled with CO gas to a pressure of 1.20 atm at 73C and then 0.5869 g is pure Ni is added. If the reaction described above occurs and goes to completion at constant temperature, what will the final total pressure in the bulb be?

Answer 1

Ni + 4CO ---> Ni(CO)4 (NOTE that the previous formula is wrong)

V = 1.5 L of CO

P = 1.2 atm

T = 73ªC or 346 K

m = 0.5869 g of Ni is added

MW of Ni = 58.7 g/mol

Find moles of CO present

Apply ideal gas law

PV = nRT

n = PV/(RT) = 1.2*1.5/0.082/(346) = 0.06344 mol of CO present

Calculate moles of Ni inside

mol = mass/MW = 0.5869/58.7 = 0.009998 mol

Note that we have CO in excess

0.009998 mol of Ni need 4X mol of CO, that is 4*0.009998 = 0.0399 mol of CO will react

Now, do a mol balance

mol of Ni initial = 0.009998 mol of Ni

mol of Ni reacted = 0.009998 mol of Ni

Mol of Ni final = 0

mol of CO initial = 0.06344 mol of CO

mol of CO reacted = 0.0399 mol of CO

mol of CO final = 0.06344-0.0399 = 0.02354 mol of CO

mol of NiCO4 = 0

mol of Ni(CO)4 produced = 0.009998 mol of NI(CO)4

mol of Ni(CO)4 final = 0.009998

Total mols in final stage = 0.02354 + 0.009998 = 0.033538 mol

NOW, apply ideal gas law

P1*V1/(T1*N1) = P2*V2/(T2*N2)

Not that V1 = V2 since bulb is fixed

T1 = T2 since no change in temperature is stated

therefore

P1/n1 = P2/n2

Solve for P2

P2 = (n2/n1)*P1 = 0.033538/0.06344 * 1.2 atm = 0.6344 atm

P2 = 0.6344 atm